Spanish fishermen in some 60 fishing boats protested on Sunday the building of an artificial reef near the disputed British territory of Gibraltar. The construction of the reef has soured relations between Madrid and London.
The fishermen claim the reef of around 70 concrete blocks — some with steel rods protruding — can snare and damage their nets, something that has stopped them from fishing there.
"What are we losing? A bay full of seafood," said fisherman Manuel Morente. "That's where we all used to fish, and now it's full of blocks."
The protest was monitored by a dozen Spanish and Gibraltar police vessels that prevented the fishing boats from getting near the reef.
Gibraltar's government, led by Chief Minister Fabian Picardo, says the reef protects fish stocks from being over-exploited.
The latest dispute has led to a spike in tensions, with Spain's Prime Minister Mariano Rajoy saying he will take all legal measures to defend his country's interests.
Among steps taken by Spain are border checks on cars entering and leaving Gibraltar, leading to long queues that can take hours to clear.
Many Spaniards, and Gibraltarians who chose to live in Spain, commute to work every day across the border.
Rajoy has defended border controls, saying they help combat the contraband of drugs and tobacco, adding that the checks were in line with security policies employed by member countries of the Schengen free travel zone to which Britain and Gibraltar do not belong.
Spain has also floated the idea of charging people entering and leaving Gibraltar 50 euros ($66) to provide compensation for the losses that the fishermen face.
Picardo has refused to back down, saying that "hell will freeze over" before Gibraltar removes the reef in compliance with Spain's demands. He has accused Spain of behaving like North Korea.
British Prime Minister David Cameron has asked the European Union to investigate the border checks. He called EU Commission President Jose Manuel Barroso to raise concerns that the checks violate the bloc's rules on free movement.
Cameron urged Barroso to send an EU monitoring team to the Gibraltar-Spain border to investigate. Both Spain and Britain are members of the 28-nation EU.
The U.K. also said it was considering taking Spain to court over the checks. Britain said Friday that it feels the checks were politically motivated and disproportionate.
Cameron has said he wants to resolve the dispute through dialogue.
The issue could be complicated by the expected arrival at Gibraltar late Sunday of British navy ships that have acted as an escort to aircraft carrier HMS Illustrious that is due to take part in pre-planned naval exercises in the Mediterranean.
The Illustrious is already in the southern Spanish port of Rota which is used by the United States as a base.
Heckle contributed from Madrid.